Tinea pedis is a dermatophyte infection of the feet, most commonly caused by Trichophyton rubrum. Clinical patterns include interdigital maceration, moccasin (hyperkeratotic) scale, and vesiculobullous eruptions. Diagnosis is clinical supported by KOH microscopy and, if needed, culture or PCR. Topical antifungals are first-line for limited disease; oral agents are used for extensive, hyperkeratotic, recurrent, or nail-involved cases. Treating concomitant onychomycosis and implementing foot hygiene are key to preventing recurrence and cellulitis.
Epidemiology and Risk Factors
- Common in adolescents and adults; higher in warm, humid climates.
- Risk factors: occlusive footwear, hyperhidrosis, communal showers/gym floors, diabetes, immunosuppression, concomitant onychomycosis.
Clinical Types
- Interdigital: pruritic, malodorous maceration and fissuring between toes (classically 4th web space).
- Moccasin (chronic hyperkeratotic): diffuse plantar scaling with accentuated dermatoglyphics; often bilateral; may extend to sides of feet.
- Vesiculobullous (inflammatory): pruritic vesicles on the medial arch or plantar surface; id reactions can occur on hands.
- Ulcerative: erosions with secondary bacterial infection in severe cases.
Differential Diagnosis
- Erythrasma (coral-red fluorescence with Wood’s lamp), contact/atopic dermatitis, psoriasis, pitted keratolysis, candidiasis, dyshidrotic eczema, keratoderma.
Diagnosis
- KOH prep of scale or vesicle roof contents to visualize hyphae.
- Culture/PCR for atypical, recalcitrant, or pre-systemic treatment confirmation.
- Assess for onychomycosis and treat concurrently.
Management
- Topical antifungals (first-line for most)
- Allylamines: terbinafine 1% cream/gel qd for 1–2 weeks (often faster cure).
- Azoles: clotrimazole, miconazole, econazole bid for 2–4 weeks.
- Ciclopirox or tolnaftate as alternatives; powders/sprays for maintenance in shoes/socks.
- Oral antifungals (for extensive, moccasin type, recurrent, or failed topical therapy)
- Terbinafine 250 mg daily for 2 weeks.
- Itraconazole 200 mg bid for 1 week (or 100 mg bid for 2 weeks).
- Fluconazole 150 mg weekly for 2–4 weeks.
- Check drug interactions and hepatic considerations.
- Adjunctive/Preventive Care
- Keep feet dry; change socks daily; breathable footwear; rotate shoes; use desiccants/antifungal powders.
- Treat hyperhidrosis (antiperspirants, iontophoresis).
- Disinfect showers/floors; wear sandals in communal areas.
- Treat onychomycosis to reduce reservoir.
- Complications
- Secondary bacterial infection/cellulitis, especially with interdigital fissures and in diabetics/lymphedema.
- Id reactions (dermatophytid) manifesting as pruritic vesicles on hands—treat primary infection; use topical steroids for symptomatic relief of id.
References (recent guidelines and key reviews)
- Dermatophyte infection management guidelines, 2022–2024.
- Comparative efficacy of allylamines vs azoles, 2021–2024.
- Preventing cellulitis with interdigital tinea management literature, 2022–2024.